Detachable auxiliary fin means for aircraft



April 17, 194

L. M. GRIFFIN DETACHABLE AUXILIARY FIN MEANS FOR AIRCRAFT Filed Aug. 5, 1945 2 Sheets-Sheet 1 April 17, 1945. l... M. GRIFFIN 2,373,677

v DETACHABLE AUXILIARY FIN MEANS FOR AIRCRAFT A Filed Aug. 5, 1945 2 Sheets- Sheet 2 meof any royalty thereon.

Patented Apr. 17, 1 945 asrasvr 'DETACHABLE AUXILIARY MEANS FOR AIRCRAFT Louis M. Griflin, Newiorleans, La.- Application August5, 1%)43, Serial No. 491,534 v 6 Claims. (e1. 244-91 (Granted under the act of March 3, 1883, as

amended April 30, 1928} 370 O. G. 757).

one another into clamping engagement withthe A The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to Thisinvention relates to fin means for the supporting surfaces of aircraft and particularly The purposeof providing such wing tip end fin A meansis to increase liftand consequently shorten the space required for take-off and thereby permitexisting planes to take off with greater loads. At high angles of attack, as during take-off and initial climb, induced'drag due to wing tip'vortices 'is quite costly in terms of efliciency. -Vertically disposed fin'members provided at the ends of the wings ofair'planes will decrease drag as muchas one third and produce an increase of some twelve percent in niaximumflift. The beneficial effects "of such fin meansare even more: pronounced at such angles of attack where planes have low aspecti-atioStf further advantage involves an increase in the rate of climb.

Since the value of fin means of the class. described is of'a negativeorder at low angles of attack or under level flight conditions where speed fis'thepr'ime factor,'this invention contemplates the provisioni'of detachable fin means of the class described-which may be released from the airplane to be dropped'tothe ground when altitude hasbeen attained,*the fin means being of *no further advantage after the attainment of 'suflicient altitude and *the fin means not usually being needed for landing-purposes on account *of the-fact that thefuel load willusually be sufiicientlydecreased at the end of the fiightto compensate for additional cargo loading and enable the plane to be landed in the available space despite its-heavier cargo-load.

Inthe light of the foregoing, the inventionicontemplates the provision of novelly constructed fin members adapted to be detachably secured adjacent the extreme ends of the airplane wing and the provision of novel means for detachably securing said fin members in such position. The fin members provided'at the ends of the airplane wingseach comprises a .fin section extending above, and substantially. vertically disposed with respectto, the, wing, a second fin section extending below and likewise. substantially vertically disposed with respect to the wing, and anintermediate clamp section joining said fin sections and adapted to embracethe end portion of the wing. The clamp section is preferably resilient and of substantially U-shapein cross section and the ends of; the clampv section normally stand awayifrom the wing embraced thereby prior to locking the fin means to the wing. The ends of vthe clam s c o L a e vthan P e z w' wing and the locking means is adapted for locking engagement with the ends of the clamp sec- .tion to maintain the same in resilient engagement with the wingin locked condition; whereby the fin means will tend to spring away from the wing, when released from locked condition in flight.

.The ends of the clamp means and the adjacent portions of the upper and lower fin sections are .provided with openings for receiving lockinglugs or'latches movable through the upper and lower skin respectively of the airplane wing, and operating means for effecting locking and unlocking movement of the locking lugs or latches comprises ,a toggle joint including an operating rod andtoggle links pivoted to said rod and respectively pivoted tosaid locking lugs or latches.

In: the drawings,

Figure 1 is a, longitudinal vertical sectional view through a wing and the fin means of my inventionillustrating the invention.

Figure 2 is a'perspective-view looking toward one end. of an airplane wing showing the .fin means ofthe invention appliedthereto. I

Figure 3 is aside viewjof' an airplane wing showing the clamp section of the fin means in its normal spread-apart condition prior to being pressed into clamping engagement with the wing,

or when unlocked.- I

Now referring to the drawings for a detailed description of the invention, the. numeral I generally indicatesan airplane wing and the numerals 2 and 3 represent the upper and lower surfaces or skins thereof respectively. A fin member generally indicated by the numeral 4 is shown applied to the wing Iadjacent one extreme end 5 thereof. One such-finmember 4 is applied :to the extremeouter end of eachwing of, the airplane. This fin member 4 may be constructed of any cheap, and preferably resilient, material having sufiicient strength under tension, such as plastic bonded plywood. The form of a single fin member 4 is roughly that of a circle with a diameter approximately equal to the chord of the wing on which it is designed to be used and the fin member 4 comprises anupper fin section 6 adapted, when the fin'member is properly ascally disposed with respect to the upper surface I 2 of the wing. I Saidfin member 4 also-includes a lower fin section 1 likewise adapted to besubstantially vertically disposed with respect to the lower surface 3 of the wing l. An intermediate clamp section 8 joins thefin sections 6 and land is adapted to embrace. the end 5 of the wing! intermediate said .fin sections. The clamp. section 8, as seen best in Figure l, is generally .of substantially Ur-shapein cross sectionandis slightly larger than the portion of ,theewingl tween the points on the respective upper and lower faces 2 and 3' of wing I with which the ends 8a and 8b of the clamp section 8= are=adapted*to engage when the fin member -is locked -incooperative relation with the wing I. 'In other words the normal condition of the resilient clamp-section! is such that the ends 8a and 82) thereof tend to stand away from the adiacentlsurtaces "2 Idnd of the wing I, as indicated in FigureBJWhen'the end-5' of the 'wing "I is received "within thezclamp section 8 rprior to locking the fin member to the wing I- in the manner indicated' in Figure '1. As indicated in the latter figure theends 8a=and "8b --of the clamp section :8 are compressed toward one another into engagement with: the respective the corresponding movement of the locking Jlathes 9 an'ii 'iI'II andthe toggleilinks ls and 20 from -the unlocked dotted line positions of these members indicated in Figure 1 to the locked full line position of said members likewise indicated in Figure 1. docking latches 9 and ID are guided in their movement in an arcuate path by I the arcuate guideways I1 and I8. In the un- *iockeiicon'dition of the latches 9 and I0, the outer resiliently clamped condition by the locking -means-now to be-described. I

The locking means comprises the are shaped docking lugs =or latches-:9 and In respectively adapted to move through -suitable lopenings II and IZ in the respective uppen and lower surfaces 2 'and -3 of thc'wing I into an'd:ou.t= of'engagement with the latchreceiving-means provided iniitheifin member I, said latter means cenveniently 1 comprising suitable openings I3Eand It i in the clamp section Send-the fin sectiom 6 respectively iorreceiving the latch member 9 andmp'enings lizand I B in the -clamp section 8 anxixfin section re- :spectively f or "receiving :the latch I 0. a'rc shaped lugs or latches O anrl' I O 'ara'positioned tively, secured to the airplane wing I.

. The operatin'gimeans ior the iatche's a and I "comprises* a to'ggle j oint consisting of the -to'ggle rlinkszle mam and themperatmg rod:24. 'The guideways i I1 :and N3 ai e slfitted" as'- indicated at -fl a and lia'a respectively for accdmmodation of the toggle links I9 and 20 respectively pivoted to -the latch 9 as at- 2 I and to the -latch m asat 22, said links is 2 and at being r pivotaily conne'eted ends thereof areretracted into, or at least flush with, the respective surfaces or skins 2 and 3 and inthe 'locked condition, of course, the locking latchl extends through the opening I3 and en- :terstheopexiing'll while the locking latch I0 extends through the opening l5 and enters the openm'g [5.

With members 4 locked to the wing ends "of an airp'lane inthe' manneriindieated iii-Figure 1, the airplane is enabledto 'ta-ke-zoffiin shorter space despite the increased loadsend, upon at- "taining altitude, the fin members 8, being no i'onge'r required, may be dropped "off i the wings. To accomplish the latter result it is only necessary to retract the operating' rc'd2'4 in a leftward direction, having reference to Figure 1, to 'bring the'lccking'latche's 9 and II] and the-"togglalinks "F9 and "Z0 intoth'e dotted line 'positiomsh'own in "said figure. 'Under'such conditionxof'course, it

:to a=pivot pin iii carried by the operatingrod u which extends into a'nfd is 'g'u-ided for mo'vement longitudinally by a guide tulrie 2 5. Pi'vt pin 23 ricl'es in diameti'ically opposed sldts at either side ot the 'g'uide t'ube 1.225 and suitable diametrically opposed slots are pro'vide'd in -th'e guide-tube 2 5 for accdmmcdationpfi the" toggle links I 9 and 20. Suitable cushion members 2I a're provided 'im' teri'orly df the elarr'ip portion 8*of the fln member 4 tor "cushioningthe engalgementfif thefin memkir l with respect to the airplane wing I 'The a cushion 'm'ember 21 1 may be 'composed of rubber or-other suitable :resmemmaterim.

In operation, the nn m'ember 4 1s 'emplaced upon' the end 5 of the w'in'g I- with"the-clamp 'se'ction l 'embracing the wing in the "manner-indicated in fiigure e, -the ends 'aa andwbot' theclamp se'ctio'n *8 iming normally spread 'apart out of eiigagemen't *with the adjacent surfaces? and' 3 'ef the wing L as likewise indicated in Figures, prior to I locking the 'fln member l to the win'g I. ln the operation of locking the tin member in ziplace' o'n the wing I'the en'ds 8a *andBb" of the I clamp section a are' spr'un'g toward each 6'ther into enga'gem'ent with-the adi acent "s'urtaces' 2 and -3 ofr' the 'wing I as indicated in 'Figure i' andthen Y zthe 'cperating rcd u is' -mo'ved ln a rightwafdhi- Fraction, 'having reference to Figure 1, eflectirig will be apparent that the pressure tending to hold the ends 8a and 8b "of the "clampsection' 8 "in fan inwardly "compressed position will be re- "leased, permitting said ends "8a and 812 "(if "the clamp "section? to sprin'g'outwardiy intothenor- :mai'coriditiondfFigureis due tothe' resilience of the clamp'sectiont, and 'suchacti'on willrtendto ..cause the'iin' members] to spring away from the wing en'dsan'd thustpos'itively; release "or detach thesamefromth wingiso' thatsaid'fin members .may drop to the ground.

.It willibe noted lthat lthearrangemerit .df .the vtogglellinks is such that whentheilatches Q9 and I10 :and the'links I19 and 20 are.' in theirlfull'lline locked ,positionvof Figure 1, an ioveridea'd .center relation is efiectedwith respectto-ithepivct points i I, taint-22 23. :It' will rbe apparent-ithattthe :fin memberdlJnayhe formedall-cof thee-same mateirial andreven of I a single .piece of material. if ,the (same: has: thez proper strength under-tension: and ,preferably :suiiicient 1 resilience to produce tthe --=spring :e'ttect desired fcr the clamp --section 8. "Alternatively; of 'courseetheifin sections Stand I and tHBPdamP SGCtiOR-SBS maybe formed as vsepa- :rate sections :andlintegrally :securedtogether, :in which event the clamprsection-iaamayibeiformed 40f u-a different and more resilient 'matei'ial 7 than ithexflnisections fiandi'l ifs desired.

-It as m nted that in the LflnaI "docked con- :iditioniioftthefimmemberet with'respect toitheaend ioffithewing: I theifinssecti'ons Ge-and :Izpreferably :haveia'sslight inboard :inclinationifrom the-vertii-:ca1,:1'asi indicated .in Figure 31.

The -tormfof eachffln memberwis roughlyathat of -ia rcirele iwith:azmameteraapprcidmatelyneqnal to-the clicrdiof the wmg for 'wh-i'chtiit .is' designed ito' be' usedithe mr sections iiwnki lieachatherefore being substantialiy semicircular.

I am =a-ware of the e'xisteriee o'f United States Patents Nos. 1;7-24';11 0, 1 ,"t63;257, 1,t57t63.6 158563i93i'relating to' wingfiins 'torsaircndft andief U. S.Patent 2528322 3 relating to releasablezsup- "porting surfaces-"fer aircraft "wings an'd 'l make noclaim=to""tl-1e subject matter diselose'd inasaid patents. 1

"Having "'thus *described -'my invention, what i I 

